Synthesis of phosphonium salts under microwave activation — Leaving group and phosphine substituents effects

Abstract

The specific nonpurely thermal effects of microwaves were evidenced according to neutral or charged leaving groups during nucleophilic substitution of benzylic electrophiles with triphenylphosphine and tributylphosphine. Microwave (MW) irradiation considerably enhanced the reactions with charged alkylating agents, especially under solvent-free conditions. Results are interpreted considering the magnitude of MW effects according to the position of the transition state along the reaction coordinates.Key words: microwave irradiation, specific effects, phosphonium salts, leaving group effects.